Compliant elastomeric shock absorbing apparatus

Abstract

A shock absorbing apparatus (200) includes a flexible membrane (204) defining an accumulator cavity, and a compression assembly defining a compression cavity. The compression assembly is disposed within the flexible membrane (204) such that viscous fluid contained within the cavities may be exchanged therebetween by a damping orifice (238), fluid conduit and or valve mechanism. The accumulator cavity deforms in response to the application of a transmitted impact load, and is capable of storing and releasing potential energy in response to the application and cessation of the transmitted impact load.

Description

TECHNICAL FIELD

[0001] This application is generally directed to the field of energy absorption apparatus and more specifically to a shock absorbing apparatus according to the preamble of claim 1 and a method for manufacturing a shock apparatus according claim 8.BACKGROUND

[0002] There are several types of apparatus that can be employed for industrial and structural uses in order to absorb energy, such as from a transmitted load. For example, high cycle blow molding apparatus employ mold or die halves which can "bounce" as a consequence of opening and closing the dies, i.e., principally the impact of closing the dies. Such bounce can produce defects in the molded product resulting in increased scrap, additional maintenance and increased downtime of the blow molding apparatus. Consequently, the throughput / efficiency of the blow molding apparatus is adversely impacted. To alleviate difficulties associated with the foregoing, conventional shock absorbers have been employed to convert the impact energy of the bounce as dissipated heat.

[0003] More specifically, these shock absorbers typically include at least one piston assembly, which is disposed within an enclosed cavity or housing, and coupled to the machine under load. In operation, a transmitted shock or impact load creates: (i) movement of the piston assembly, (ii) a change in pressure of a contained incompressible hydraulic fluid in the cavity, and (iii) flow through at least one orifice that results in conversion of the applied kinetic energy to heat. The force of the transmitted shock or impact load is reduced by the shock absorber, thereby lowering the transmitted load from other parts of the machine or other attached structure.

[0004] For proper operation, shock absorbers as described above require at least one dynamic seal interposed between the moving parts to prevent fluid leakage, and / or the ingestion of air into the hydraulic cavity of the housing. Inasmuch as blow molding or other apparatus routinely undergo a high number of cycles, it is common for the dynamic seals to fail prematurely, requiring costly repair and maintenance. Additionally, the replacement of either the hydraulic seals, or the entire shock absorber assembly, can adversely impact manufacturing schedules or other time-critical events for the purpose of repairing and / or replacing the affected assemblies. It will be appreciated that avoiding down-time for such high throughput machines is an ongoing and important goal. An elastic-walled hydraulic mounting for automobile engines of DE 26 18 333 A1 is designed to absorb low frequency high amplitude engine vibration whilst transmitting high frequency low amplitude support vibration. It has primary and secondary cells containing hydraulic fluid. Part of the cell walls may be of rubber and a bleeding orifice communicates between the cells. The mounting comprises a hollow unit which is traversed axially by a vertical bolt and subdivided by a horizontal metal diaphragm plate. The top of the bolt attaches to an engine bracket, and external flanges at diaphragm level attach to the chassis. Metal cones with rubber rings form the top and bottom of the unit resp. and inclined plates from the diaphragm form the side walls. The second fluid chamber of DE 297 24 898 U1 is incorporated with a volume accommodating a medium restricted by a second limiting device. An intermediate component is arranged between the first and second fluid chambers and has at least one shock absorbing aperture through which medium can flow from the first fluid chamber into the second and vice versa. The shock absorber of FR 2 398 226 A1 has a base with a central reservoir containing hydraulic fluid. The fluid container has a central column with a central to receive a needle valve. The outside of the column is fitted with a cone made from elastic material. The top of the absorber has a cover plate over a cylinder in the base. The needle valve is fixed to the underside of the plate and the outside of the cone is fixed to the inside of the inner cylinder.

[0005] It is, therefore, desirable to provide an effective and reliable shock absorbing apparatus which mitigates the need for dynamic seals and the failure modes associated therewith. Furthermore, it will be appreciated that there is a competing and prevalent need to reduce complexity, improve reliability, and lower associated costs of such high cycle, dynamic shock absorbing apparatus.BRIEF DESCRIPTION

[0006] The shock absorbing apparatus according claim 1 is characterized by two pin members disposed in axial relation on opposite sides of the plate and movable disposed in relation to the at least one orifice, in which transmitted loads acting on the flexible housing on either side of the plate cause movement of the two pin members relative to the at least one orifice to create a variable orifice diameter

[0007] In at least one version, the flexible housing can be defined by at least one elastomeric section bonded to at least one support plate. In at least one embodiment, a pair of housing portions are provided, each having at least one elastomeric section bonded to a mounting plate and a striker plate, respectively. In one version, a single orifice is defined in a center plate although this number can be suitably varied and sized to enable damping characteristics to be suitably tuned.

[0008] Two shaped pin members are provided to define a variable orifice diameter wherein the pin members can be defined by a tapered configuration that effectively reduces the flow area when one of the pin member is moved into the orifice while under load. In addition and according to at least one embodiment, at least one spring can be provided within the defined housing to provide an additional biasing force along with the restoring force provided by the flexible elastomeric housing and also to prevent a compressive set.

[0009] According to another embodiment, the herein described shock absorbing assembly can be configured to receive impact or shock loads at respective ends of the defined flexible interchangeable according to a housing, and in which a biasing spring can be provided in each fluidic chamber in the housing interior such that the adjacent fluid chamber and accumulation chambers are symmetric.

[0010] The method for manufacturing a shock absorbing apparatus without requiring sliding hydraulic seals, comprising: bonding outer ends of a first elastomeric section to a first base plate to create a first housing section; bonding outer ends of a second elastomeric section to a second base plate to create a second housing section; disposing an orifice plate between the first and second housing sections, the plate having at least one orifice; connecting the two housing sections together to form an enclosed flexible housing, in which the orifice plate is sandwiched between the first and second base plates and extends through the defined housing to define interior fluidic chambers; bonding a striker plate to inner ends of the elastomeric section of each housing portion, each striker plate being axially aligned with the orifice at respective ends of the flexible housing; disposing two pin members within the defined orifice in order to create a variable orifice diameter, wherein the two pin members disposed in axial relation, each pin member being disposed on opposing sides of the plate having the at least one orifice; adding hydraulic fluid to the interior of the defined housing; and attaching each of the base plates of the housing to a structure under load, wherein impact loads to the striker plate bonded to either the first or second housing sections of the flexible housing causes pressurization and movement of the contained hydraulic fluid between defined fluidic chambers through the at least one orifice in order to effect shock absorption.

[0011] In one version, the fluidic chambers can be defined using a fixed plate that is disposed within the interior of the flexible housing, in which the fixed plate further includes the at least one orifice. One or more orifice holes can be sized and configured for a desired damping level when fluid is caused to pass therethrough.

[0012] Each end of the defined housing, in at least one version, can include at least one striker or contact plate that is axially aligned at an end of the flexible housing with the defined orifice that is configured to effect damping in response to an applied load.

[0013] Two pin members are added to the interior of the housing, the pin members could have a tapered configuration that can be translated axially into and out of the orifice based on loading conditions, and thereby creating a variable orifice diameter. For example and according to one version, the pin member is assembled using fasteners to the striker plate and reduces the effective flow area when moved into the orifice. In at least one version, a pair of tapered pin members can be provided, each of these members being axially and symmetrically aligned with one another.

[0014] In addition, at least one spring can also be optionally included within the interior of the housing and more specifically within each of the defined fluidic chambers in order to additionally provide a biasing or restoring force along with the elastomeric material of the housing and / or to prevent compression of the herein described apparatus.

[0015] Advantageously, the herein described shock absorbing apparatus is simpler and easier to assemble than prior known versions based on a fewer number of required parts. The herein described shock absorbing apparatus performs reliably, but without requiring reciprocating piston assemblies and associated hydraulic sliding seals. As a result, the herein described apparatus has a longer overall service life as compared to prior designs, and particularly in working environments that are usually characterized by frequent or high loading cycles.

[0016] In addition, the herein described apparatus is relatively easy and inexpensive to manufacture as compared to prior art versions. For example, aspects of the housing can be injection molded according to at least one version. In addition, the herein described apparatus is simple in terms of assembly and also for purposes of mounting to a specified structure or machine that is under load for purposes of shock absorption.

[0017] For manufacturing purposes, the same mold can be used with various durometer / hardness properties of elastomer to provide stiffness variation. Similarly, different orifice sizes can utilize the same plate "blank". This allows the same components and manufacturing process / tools to be used for multiple applications of the herein described apparatus.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] An embodiment will be described in detail, with reference to the following figures, wherein like designations denote like members. Fig. 1 is a sectioned view of a prior art shock absorbing apparatus; Fig. 2 is an exploded assembly view, shown partly in section, of a shock absorbing apparatus made in accordance with an exemplary embodiment; and Fig. 3 is a sectioned view of the shock absorbing apparatus of Fig. 2. DETAILED DESCRIPTION

[0019] The following relates to an embodiment of a shock absorbing apparatus that relies upon at least one elastomeric element or membrane to define a highly flexible housing containing a hydraulic fluid that can be attached to a structure or machine under load. The apparatus reliably reduces transmitted shock loads from other parts of a machine or other structure.

[0020] In the embodiment, the shock absorbing apparatus reduces transmitted shock loads without the requirement for sliding dynamic seals to move a hydraulic fluid through a damping orifice and / or separate spring biasing elements to return the elastomeric membrane to its original shape / configuration for subsequent work cycles. As such, the hydraulic shock absorbing apparatus of the present disclosure is particularly advantageous for use in environments characterized by high cyclic loading such as, for example, blow molding apparatus for fabricating plastic containers / bottles. It will also be readily apparent that the shock absorbing apparatus described herein can be employed for nearly any application that requires impact and / or shock load absorption.

[0021] For background purposes, reference is made to Fig. 1 which depicts a typical shock absorbing apparatus 100 comprising a piston assembly 106 disposed within, and supported by, a cylinder 120 containing a hydraulic damping fluid 108. More specifically, the piston assembly 106 includes a piston head 110, at one end, disposed within, and acting against, the hydraulic damping fluid of the hydraulic cylinder 120, and a cylindrical piston rod 114, at an opposing end, connected to the piston head 110.

[0022] In operation, the piston assembly 106 moves with, and is responsive to, a transmitted impact or shock load of the blow molding apparatus while the cylinder 120 is attached to a fixed support, or another portion, of a machine. More specifically, the transmitted shock or impact load causes axial movement of the piston assembly 106, including the piston head 110 against the hydraulic fluid, pressurizing same and causing movement of the fluid though at least one defined orifice 130 to an accumulator 136. This movement results in a reduction in transmitted force to the remainder of the connected structure as the energy of the shock load is dissipated over the stroke of the unit, i.e., as heat generated by the shearing action of the hydraulic fluid. The piston assembly 106 is configured to move axially in a reciprocating fashion in response to the transmission and cessation of load while a biasing coil spring 128 stores a portion of the kinetic energy of the piston assembly 106 as potential energy in the coil spring 128. With each cycle, the impact load displaces the piston head 110 so as to force the damping fluid through the damping orifice 130 in the piston head 110. With the cessation of the impact load, the coil spring 128 is operative to return the piston assembly 106 of the shock absorbing apparatus 100 to its initial or original position. To prevent leakage of the contained pressurized hydraulic fluid during movement of the piston head 110, a dynamic (frictional) seal 140 is provided. Under conditions typified by high cyclic loading, this dynamic seal 140 is prone to failure. Consequently, shock absorbing apparatus of the prior art require frequent replacement which adversely impacts throughput and machine efficiency.

[0023] Referring to Figs. 2 and 3, a shock absorbing apparatus 200 in accordance with an exemplary embodiment is defined by a flexible housing 204 that is made substantially from a fluid-impermeable elastomeric material. According to this specific embodiment, the shock absorbing apparatus 200 is defined by a pair of housing portions 206, 208, as well as an orifice plate 212. Each of the housing portions 206, 208 are commonly defined by a section 210 of an elastomeric material of suitable shape, in this instance circular, and in which each elastomeric section 210 has an outer periphery 217 that is bonded to the inner peripheral edge of a mounting plate 216. It will be understood that the shape assumed for the mounting plates 216 and elastomeric sections 210 is exemplary and other configurations could be contemplated.

[0024] An inner periphery 219 of each elastomeric section 210 is further bonded to a striker plate 220. When assembled, each of the bonded elastomeric sections 210 of the housing portions 206, 208 form a complementary and substantially C-shaped configuration in which the mounting plates 216 each extend radially from the elastomeric section 210 and in which the striker plate 220 forms the center of each outwardly bowed housing portion 206, 208. In this embodiment, each of the housing portions 206, 208, including the elastomeric material section 210, are identical. It should be noted, however, that each housing portion 206, 208 could be configured with different material characteristics. For example, the thickness, shape and or material of the elastomeric sections of the first and second housing portions 206, 208 can be varied from one another in order to produce different responses under load. In the described embodiment, the flexible elastomeric sections may be fabricated from a rubber material, including natural rubber, fluoroelastomer, fluorosilione, silicone, EPDM, butyl rubber, nitrile rubber and the like. The flexible elastomeric material employed therein may have a shear modulus greater than about 29992 bar (4.35 × 10 5< psi), a bulk modulus greater than about 15168 bar (2.2×10 5< psi), a maximum elongation greater than about 100% from an original size / length, and a durometer of between about between about thirty (30) to about seventy (70) on a Shore A hardness scale.

[0025] Each mounting or support plate 216 according to this embodiment is formed as a substantially planar section made from a suitable metal, plastic or elastomeric material, provided each of the plates can provide structural support. In at least one version, each of the mounting plates 216 could also be made from an injection molded plastic. The mounting plates 216 are defined by an inner peripheral end and an opposing outer peripheral end with a circular opening being formed at the center of each mounting plate 216 which is bounded by the inner peripheral edge of the mounting plate 216. An annular groove 226 is formed on an opposing surface of each mounting plate 216 at the peripheral inner end relative to the bonded elastomeric section 210. The bonding of the elastomeric sections 210 to the striker and base plates 216, 220 can utilize adhesives, activated during the molding process, or as a post-molding standalone agent that creates or otherwise creates a durable fluid-tight seal. According to this embodiment, the annular groove 226 of each housing portion 206, 208 is configured to receive an O-ring 229 or other form of static sealing member.

[0026] The striker plates 220 are made from a durable material, such as a thermoset wear-resistant plastic and are commonly defined by a substantially cylindrical configuration. Each striker plate 220 is sized to substantially correspond with the thickness of the solid elastomeric section 210 and includes a center through opening 224 sized to receive a fastener 228, such as a counter sunk fastener, the fastener 228 having a length that extends into the interior 240 of the housing 204 when attached, as shown in Fig. 3. Each of the two mounting plates 216 and the sandwiched orifice plate 212 are defined by an aligned series of mounting holes 230 which are exterior to the formed flexible housing 204. The mounting holes 230 enable attachment of the flexible housing 204 to a structure or machine (not shown) using fasteners (not shown). It should be noted that this embodiment depicts striker or impact plates 220 as part of each housing portion 206, 208. Alternatively, only one of the housing portions can be provided with a striker or impact plate 220.

[0027] The orifice plate 212 according to this exemplary embodiment is defined by a planar member made from plastic, metal, composite or other durable material that is sized and configured to extend through the interior of the defined housing 204 with the outer end of the orifice plate 212 being sized to complement the mounting plates 216, including the mounting holes 230. At least one orifice 238 formed at substantially the center of the orifice plate 212 is axially aligned according to this embodiment with the through openings 224 of the striker plates 220, when assembled. The orifice plate 212 divides the hollow interior 240 of the housing 204 into adjacent substantially hemispherical chambers 242, 246 that are fluidically interconnected by the defined orifice 238. In the context used herein, "fluidically" means a fluid connection, or the type of connection, between two portions, cavities or chambers of the hydraulic shock absorbing apparatus, i.e., that the cavities are in fluid communication. Though only a single orifice 238 is provided according to this embodiment, one or more orifice(s) can be suitably provided and sized in order to effectively tune the amount of damping required. According to this embodiment, the orifice plate 212 further includes a pair of outwardly extending annular rings 234 radially exterior to the housing 204 that are sized and configured to fit within corresponding grooves 237 which are formed within the inner facing side of a corresponding mounting plate 216 to further retain the assembly 200 in a press fit. Following the above described press fit assembly of the housing portions 206, 208, a quantity of hydraulic fluid 250 can be added to the hollow interior 240 of the housing 204. According to this embodiment, the hydraulic fluid 250 can be added to the through opening 224 formed in one of the striker plates 220, forming a sealable fill port, and prior to attaching the fastener 228.

[0028] According to this specific embodiment and still referring to Figs. 2 and 3, at least one pin member 252 can be optionally disposed within the hollow interior 240 of the defined housing 204. More specifically and according to this exemplary embodiment, a pair of hollow pin members 252 can optionally be provided, each pin member 252 having a conical tapered configuration defined by a distal end opening 254 having a first diameter and a proximal end opening 256 having a second diameter that is larger than the first diameter. According to this exemplary embodiment, the pin members 252 each include a proximal opening 258, Fig. 2, that receives the extending end of fasteners 228 at each end of the housing 204. When positioned in the manner shown in Fig. 3, the application of a transmitted axial load 284 to the housing 204 will cause the pin members 252 to be moved into the orifice 238, thereby reducing the effective flow area and creating a variable orifice diameter.

[0029] In addition, a pair of springs 266 can be optionally provided in the hollow interior 240 and aligned with the orifice 238 and the striker plates 220 in order to provide a biasing or restoring force in addition to that of the elastomeric housing 204. In this embodiment, each of the springs 266 are mounted between the striker plate 220 and the orifice plate 212 in each respective fluidic chamber 242, 246 with the pin member 252 extending through the center of the spring 266. According to this specific embodiment and when assembled, the springs 266 are axially aligned with the orifice 238, as well as the center openings 224 of each striker plate 220 and with the spring ends being in engagement between a striker plate 220 and the orifice plate 212 in each defined fluidic chamber 242, 246.

[0030] Fasteners (not shown) from a machine or other structure, such as threaded or other forms of fasteners, secure the herein described optional assembly through the aligned openings 230 of the mounting plates 216 and the sandwiched orifice plate 212, thereby fixedly attaching the assembly to a structural component.

[0031] In operation and still referring to Figs. 2 and 3, the herein described shock absorbing apparatus 200 can be disposed between respective die portions of a blow molding machine (not shown) and mounted using fasteners attached through the aligned holes 230 of the mounting plates 216 and the orifice plate 212. As attached, one of the striker plates 220 is aligned in relation to the movable die portion (not shown) of the machine. As the die is closed, the die engages the striker plate 220 as depicted by arrow 284, generating a compressive load against the flexible elastomeric housing 204 and more specifically the elastomeric section 210 of the housing 204. This causes an inward deformation of the flexible housing 204, resulting in the hydraulic fluid 250 contained in the first fluidic chamber 242 to be pressurized and forced through the orifice 238 and into the adjacent second fluidic chamber 246 with the optional tapered pin member 252 also being advanced into the orifice 238 based on the application of load.

[0032] The shearing of the contained fluid 250 through the orifice hole(s) and the flexion of the herein described elastomeric housing 204 acts to convert the energy of the applied load from the machine into heat that is dissipated to the environment. Following the application of load, the elastomeric nature of the housing 204 provides a restoring force to revert the housing 204 to its original shape in the direction of arrow 288, with the hydraulic fluid 250 being restored to the fluidic chamber 242 and under the additional biasing force of the optionally provided springs 266.

Claims

1. Shock absorbing apparatus (200) comprising: a flexible housing (204) substantially formed from at least one fluid-impermeable elastomeric section (210) and defining an interior, a plate (212) disposed within the interior of the housing (204) and having at least one orifice (238), the plate (212) creating adjacent chambers containing a hydraulic fluid that are fluidically connected by the at least one orifice (238); at least one mounting plate (216) for connecting the housing (204) to a structure that is under load in which transmitted loads acting on the flexible housing (200) from the structure cause a pressurized hydraulic fluid to move between the adjacent chambers through the at least one orifice (238) to provide shock absorption; in which the shock absorbing apparatus (200) is characterized by two pin members (252) disposed in axial relation on opposite sides of the plate (212) and movable disposed in relation to the at least one orifice (238), in which transmitted loads acting on the flexible housing (204) on either side of the plate (212) cause movement of the two pin members (252) relative to the at least one orifice (238) to create a variable orifice diameter.

2. Shock absorbing apparatus of claim 1, in which outer ends of the at least one elastomeric section (210) are bonded to the at least one mounting plate (216).

3. Shock absorbing apparatus of claim 1, wherein the housing (204) includes at least one striker plate (220) that is bonded to the at least one elastomeric section (206, 208) and aligned with the orifice (238), the at least one striker plate (220) being configured to receive a transmitted load.

4. Shock absorbing apparatus of claim 3, in which the at least one striker plate (220) is made from a non-metallic, abrasion resistant material.

5. Shock absorbing apparatus of claim 1, including at least one biasing spring (266) disposed within the interior of the housing (204).

6. Shock absorbing apparatus of claim 5, including a biasing spring (266) disposed within each fluidic chamber.

7. Shock absorbing apparatus of claim 1, in which the at least one mounting plate (216) and the plate (212) having the orifice (238) include aligned mounting holes (230) that enable attachment of the housing (204) to a structure under load.

8. Method for manufacturing a shock absorbing apparatus (200) without sliding hydraulic seals, the method comprising: bonding outer ends of a first elastomeric section (210) to a first base plate (216) to create a first housing section (206); bonding outer ends of a second elastomeric section (210) to a second base plate (216) to create a second housing section (208); disposing an orifice plate (212) between the first and second housing sections (216), the plate (212) having at least one orifice (238); connecting the two housing sections (206, 208) together to form an enclosed flexible housing (204), in which the orifice plate (212) is sandwiched between the first and second base plates (216) and extends through the defined housing (204) to define interior fluidic chambers; bonding a striker plate (220) to inner ends of the elastomeric section (210) of each housing portion (206, 208), each striker plate (220) being axially aligned with the orifice (238) at respective ends of the flexible housing (204); disposing two pin members (252) within the defined orifice (238) in order to create a variable orifice diameter, wherein the two pin members (252) disposed in axial relation, each pin member (252) being disposed on opposing sides of the plate (212) having the at least one orifice (238); adding hydraulic fluid to the interior of the defined housing (204); and attaching each of the base plates (216) of the housing (204) to a structure under load, wherein impact loads to the striker plate (220) bonded to either the first or second housing sections of the flexible housing (204) causes pressurization and movement of the contained hydraulic fluid between defined fluidic chambers through the at least one orifice (238) in order to effect shock absorption.

9. The method of claim 8, wherein the pin members (252) have a tapered configuration.

10. The method of claim 8, including - the step of providing at least one biasing spring (266) in the interior of the flexible housing (204); or - the step of providing at least one biasing spring (266) in the interior of the flexible housing (204) wherein biasing springs (266) are provided in each fluidic chamber of the housing (204).

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